Die-casting machine

ABSTRACT

A die-casting machine is described which includes at least one cylinder/piston assembly. Each assembly has main, ejector and core pistons and cylinders. The main cylinder is stationary and holds a piston which reciprocates to bring the molds together for metal injection or apart for releasing a die casting. A portion of the interior of the main piston constitutes an ejector cylinder having an ejector piston and a portion of the interior of the ejector piston constitutes a core cylinder having a core piston. The present invention is more compact and less complex than conventional die-casting machines.

This invention relates to a die casting machine wherein the ejectormechanism is telescoped within the main piston and the core mechanism istelescoped within the ejector cylinder where both the ejector mechanismand core mechanism travel with the main piston.

In a conventional die casting machine a frame is provided and a fixed orstationary plate upon which one-half of the mold for making the part ismounted on the frame. The other half of the mold is mounted upon amoving plate which allows the cast part to fall out of the machine whenin the open position and the moving plate is clamped shut withsufficient force to contain the molten metal while the mold is beingfilled. In operation, the part separates from the half mold on the fixedplate (the cover half) and is retained on the half mold of the movingplate (the ejector half) as it moves open following solidification ofthe molten metal which was injected into the mold cavity. The part whichwas retained on the moving or ejector half of the mold must then beejected from it to fall out or be transferred out of the machine. Theone-sided motion described above is one of the major causes for thevarious and complicated types of automatic part-transfer mechanismsassociated with conventional casting machines which have beenretrofitted with some sort of part-transfer. The same problem thenarises as the part is indexed to a secondary operation such as trimmingwherein a similar one-sided machine is used. The part-transfer carrieris required to have both an indexing function and a lateral movement tomatch the plate closing and opening stroke as the part is brought into afixed position for the desired operation.

This conventional form of machine was greatly improved upon by themachine shown in the U.S. Pat. to Perrella, 4,013,116 which issued onMar. 22, 1977. This machine is much simpler than conventional devices inthat the part was cast, indexed and removed from the machine fortrimming without any lateral movement of the part. During processing thepart is in a fixed plane and is transferred in that plane. The castingmachine has balanced forces in which both plates and mold halves or diesare moved equal distances to and from the part plane and this balancedmovement of mass cancels out the normal shock of starting and stoppingheavy plates and tools, equalizes thermal expansion differences andautomatically centers load deflections.

The machine described in U.S. Pat. No. 4,013,116 consists of a frame,mold mounting plates and hydraulic closing and opening cylinders havinga simple deceleration system to eliminate closing shock. A moldconfiguration is provided and is adaptable to a large variety of partstyles and is of pre-determined registry in the machine plates so as toeliminate mold miss-match because of thermal expansion of poor die setpractices. Metal-injection of the machine is provided with an infinitelyvariable control capable of presetting to any desired speed or pressure,together with a self-contained molten metal supply with electricresistance heaters therein.

A self-contained hydraulic power system is incorporated, usingfire-resistant fluid. Provision is made to pre-heat the molds prior tothe first shot. The machine features a self-contained heat unit forcooling the molds and eliminating lime deposits in the cooling passagesall of which is automatically connected to the mold during installationwithout hoses or pipes.

While the machine of Perrella et al is in commercial use, there is aneed for a more compact design wherein the same performance is achievedwith fewer individual components thus reducing the number of precisioncomponents necessary.

According to one embodiment of the present invention there is provided adie-casting machine of the balanced dual movement type in which bothhalves of the molds or dies are moved equal distances from the partplane comprising:

a) two stationary, main cylinders,

b) support means for mounting front ends of the stationary, maincylinders in spaced, face-to-face relationship, and for each stationary,main cylinder,

c) a hollow, main piston having an open front end and a rear wall, andslidable in that main cylinder from a forward mold halves engagingposition to a retracted, mold halves separated position, the hollowforming a casting ejector cylinder,

d) a mold half mounting means attached to the front end of the mainpiston,

e) a hollow casting ejector piston having front and rear walls andslidably mounted for telescoping movement in the casting ejectorcylinder,

f) a core cylinder attached to a central portion of the rear wall of theejector piston,

g) a core piston slidably mounted telescoping movement in the corecylinder and extending forwardly along the hollow of the ejector pistonto slidably extend through a central portion of the front wall of theejector piston,

h) a core plate attached to a front end of the core piston for movementtherewith, a core rod or rods attached to the core plate and slidablyextending through the mold half mounting means,

i) an ejector plate attached to a front end of the ejector piston formovement therewith, an ejector rod or rods attached to the ejector plateand slidably extending through the mold half mounting means, whereby, inoperation

i) with both mold halves held closed together at a molding plane byfluid in their respective main cylinders urging the main cylindersforwardly with a predominant force provided by one of the maincylinders,

ii) the core pistons are moved forwardly by fluid pressure in theirrespective core cylinders to place the core rods in the cavity betweenthe mold halves,

iii) the ejector rods are held rearwardly in their respective moldhalves, flush with the cavity wall surface thereof by fluid pressure inthe respective casting ejector cylinder, and

iv) a die casting is cast in the mold cavity,

v) the core pistons and core plate are moved rearwardly by fluidpressure in the core cylinders to remove the core rods from the moldhalves, and then

vi) with the ejector rods resiliently held forwardly by fluid pressurein their respective casting ejector cylinders, the mold halves are movedrearwardly by fluid pressure in their respective main cylinders so thatthe ejector rods dislodge the die casting from the mold halves.

According to another embodiment of the present invention there isprovided a die casting machine having one fixed mold mounted to theframe and one travelling mold mounted on a reciprocating piston, saiddie casting machine having reciprocating main, ejector and core pistonswherein there is at least one stationary main cylinder, at least onereciprocating main piston which brings the molds together for metalinjection or apart for releasing a die casting, said main piston havingtelescoped therein an ejector cylinder, an ejector piston in saidejector cylinder, said ejector piston having telescoped therein a corecylinder and a core piston in said core cylinder.

In the accompanying drawing which illustrates, by way of example, anembodiment of the present invention, there is shown a partly sectionedside view of one half of a die-casting machine of the balanced dualmovement type in which the other half of the machine not shown isidentical.

Generally designated 1, the machine comprises:

a) two stationary, main cylinders, one of which is shown and designated2,

b) support means, in the form of two spaced, parallel tie bars, one ofwhich is shown and designated 4, for mounting front ends of thestationary, main cylinders, such as front end 6 of main cylinder 2, inspaced face-to-face relationship, and for each stationary, main cylindersuch as 2

c) a hollow, main piston 8 having an open front end 10 and a rear wall12, and slidable in that main cylinder 2 from a forward mold halvesengaging position in plane XX to a retracted mold halves separatedposition in plane YY, the hollow 14 forming a casting ejector cylinder,

d) a mold half 40 mounting means attached to the front end of the mainpiston 8,

e) a hollow, casting ejector piston 18 having front and rear walls 20and 22 respectively, and slidably mounted for telescoping movement in afront end 10 of the main piston 8,

f) means, generally designated 24, for resiliently urging the ejectorpiston 18 out of the casting ejector cylinder 14,

g) a core cylinder 26 attached to a central portion of the rear wall 22of the ejector piston 18,

h) a core piston 28 slidably mounted for telescoping movement in thecore cylinder 26 and extending forwardly along the hollow 30 of theejector piston 18 to slidably extend through a central portion of thefront wall 20 of the ejector piston 18,

i) a core plate 31 attached to a front end 34 of the core piston 28 formovement therewith, a core rod or rods 32 attached to the core plate 31and slidably extending through the mold half mounting platen 16,

j) an ejector rod or rods 36 attached to the ejector plate 37 mounted onthe front end 38 of the ejector piston 18 for movement therewith, therod or rods 36 slidably extending through the mold half mounting means,whereby, in operation

i) with both mold halves 40 and 42 shown chain-dotted held closedtogether at a molding plane XX by fluid in their respective maincylinders, such as 2, urging the main cylinders forwardly with apredominant force provided by one of the main cylinders,

ii) the core pistons, such as 28, held forwardly by fluid pressure intheir respective core cylinders, such as 26, to place the core plate 31as shown in a forward position such that core rod 32 enters into thecavity 46 between the mold halves 40 and 42,

iii) the ejector plate 37 as shown is held rearwardly such that ejectorrods 36 and 48 are maintained flush with the cavity wall surface intheir respective mold halves 40 and 42 respectively by fluid pressure inthe respective casting ejector cylinder, such as 14, and

iv) a die casting 50 cast in the mold cavity 46,

v) the core pistons, such as 28, may be moved rearwardly by fluidpressure in the core cylinders, such as 26, to remove the core plate 31and core rods 32 and 44 from cavity 46 between the mold halves 40 and42, the core plate 31 may be adjusted by adjusting the length of thepiston using the bolt on the piston which extends from the back of themachine, and then

vi) the mold halves 40 and 42 are moved rearwardly by fluid pressure intheir respective main cylinders, such as 2, while the ejector plate 37and ejector rods 46 and 48 are moved forwardly by fluid pressure intheir respective casting ejector cylinder 14, so that the ejector rods36 and 48 dislodge the die casting 50 from their respective mold halves40 and 42.

The stroke of the main piston 8 is limited between the end faces 68, 69of cylinder 2. The cylinder has fluid inlet ports 80 and 82.

The mold half 40 is attached to the front end 10 of the main piston 8 byconventional means.

The hollow, casting ejector piston 18 comprises a cylinder 88, frontwall plate 20 and rear wall collar 22.

The means 24 resiliently urging the ejector piston 18 out of the castingejector cylinder 14 comprises a rod 92 for urging the rear wall collar22 rearwardly by means of a compression spring 94. The other end ofejector rod 92 extends through the rear wall of collar 22 to which it isadjustably fastened by adjusting nuts 97. The front end of ejectorpiston 20 is connected by spacer 98 to ejector plate 37. Ejector rod orrods 36 are attached to an ejector plate 37. The ejector plate isslidable on guide pins, such as 112. By externally adjusting theadjusting nuts 97, the ejector plate 37 and ejector rods 36 may beadjusted relative to the face of mold half 40.

The stroke of the core cylinder 26 is limited between the end faces 99,100 of the core cylinder. Fluid ports are provided at each end 99, 100of the core cylinder 26.

The core piston 28 includes a rod 108 extending forwardly along thehollow 30 of the ejector piston 18 to slidably extend through a centralportion of the front wall 20 of the ejector piston 18.

The core rods 32 are mounted on a core plate 31 which is mounted on theleading end of the rod 108 for movement therewith. The core plate 31 isslidably located relative to the mold 40 by a plurality of guide pinssecured to the mold securing means, one of which is shown and designated112.

From the description it will be seen that when the main piston 8 ismoved relative to the main cylinder 2, the ejector cylinder 14 and thecore retracting cylinder 26 both move with the main piston 8. However,the ejector piston 18 and the core piston 28 may both be movedindependently of each other and relative to the main piston 8 alongtheir respective cylinders 14 and 26 respectively.

The rear position of the core plate 31 is shown in dotted outline anddesignated as 120 and the forward position of the ejector plate 37 isshown in dotted outline and designated as 122.

It will be appreciated that mold halves 40 and 42 may be of the typedescribed in U.S. Pat. No. 4,637,451 dated Jan. 20, 1987, Perrella etal; also, the molten metal supply and injection system, and the diecasting transfer system may be of the type disclosed in U.S. Pat. No.2,009,645 dated Sep. 20, 1979, Perrella et al.

While the instant invention has been primarily described herein withrespect to die casting machines of the balanced dual movement type inwhich both halves of the molds or dies are moved equal distances fromthe part plane utilizing two opposed stationary main cylinders forreciprocating main pistons which bring the molds together for metalinjection, it will be recognized by those skilled in the art that thisinvention may also be incorporated in rebuilding of conventional diecasting machines in which a fixed or stationary plate is mounted on onehalf of the frame upon which one half of the mold is mounted. The otherhalf of the mold is mounted on a moving piston. The moving cylinder ofconventional machines may be replaced by a main piston having an ejectorpiston and core piston telescoped therein for movement therein asdisclosed in this application without deviating from the scope of thisinvention.

I claim:
 1. A die casting machine (1) having reciprocating main (8), ejector (18) and core pistons (28), wherein there is at least one stationary main cylinder (2), at least one reciprocating main piston (8) which brings the molds (40, 42) together for metal injection or apart for releasing a die casting, characterized by a portion of the interior of said main piston (8) constituting an ejector cylinder (14), with an ejector piston (18) in said ejector cylinder (14), a portion of the interior of said ejector piston constituting a core cylinder (26), with a core piston (28) in said core cylinder (26).
 2. The die casting machine of claim 1 in which the ejector piston (18) is connected to an ejector plate (37), and means are provided for adjusting the longitudinal position of the ejector piston (18) and the ejector plate (37).
 3. The die casting machine of claim 2 in which the core piston (28) extends from the back of the machine, means for connecting the core piston (28) to the core plate (31) and means are provided for adjusting the longitudinal position of the core piston (28) and core plate (31).
 4. A die casting machine of the balanced dual movement type in which the molds (40, 42) are moved equal distances from the part plane, two opposed stationary main cylinders (2) for reciprocating main pistons (8) which bring the molds (40, 42) together for metal injection, or apart for releasing a die casting, characterized by a portion of the interior of each main piston (8) constituting an ejection cylinder (14), with an ejector piston (18) in each ejector cylinder (14), a portion of the interior of said ejector pistons (18) constituting a core cylinder (26), with a core piston (28) in said core cylinder (26).
 5. The die casting machine of claim 4 in which the ejector piston (18) is connected to an ejector plate (37), and means are provided for adjusting the longitudinal position of the ejector piston (18) and the ejector plate (37).
 6. The die casting machine of claim 5 in which the core piston (28) extends from the back of the machine, means for connecting the core piston (28) to the core plate (31) and means are provided for adjusting the longitudinal position of the core piston (28) and core plate (31).
 7. A method of operating a die casting machine (1) having reciprocating main (8), ejector (18) and core pistons (28) wherein there is at least one stationary main cylinder (2), at least one reciprocating main piston (8) which brings the molds (40, 42) together for metal injection or apart for releasing a die casting, characterized by a portion of the interior of said main piston (8) constituting an ejector cylinder (14), with an ejector piston (18) in said ejector cylinder (14), an ejector plate (37) attached to said ejector piston (18), ejector rods (36) attached to said ejector plate (37), a portion of the interior of said ejector piston constituting a core cylinder (26), with a core piston (28) in said core cylinder (26), a core plate (31) attached to said core piston (28), core rods (32) attached to said core plate (31) comprising the steps ofapplying fluid pressure in said stationary main cylinder (2) to move the main piston (8) and close the molds (40, 42) while transporting the ejector cylinder (14) and core cylinder (26), applying fluid pressure in said core cylinder (26) to place the core rod or rods (32) in the cavity between the molds (40, 42), retaining fluid pressure in the ejector cylinder (14) so that said ejector rods (36) are flush with the mold surface, injecting a casting in the mold cavity, reversing the fluid pressure in the core cylinder (26) to retract the core rods (32) from the molds (40, 42), reversing the fluid pressure in the main cylinders (2) to remove the main pistons (8) from the part plane while applying fluid pressure to the ejector cylinder (14) to advance the ejector piston (18) and push the casting from the mold, reversing the fluid pressure in the ejector cylinder (14) to return the ejector piston (18) and ejector rods (36) to their starting position.
 8. A method of operating a die casting machine of the balanced dual movement type in which both molds (40, 42) are moved equal distances from the part plane, two opposed stationary main cylinders (2) for reciprocating main pistons (8) which bring the molds (40, 42) together for metal injection, or apart for releasing a die casting, characterized by a portion of the interior of each main piston (8) constituting an ejection cylinder (14), with an ejector piston (18) in each ejector cylinder (14), a portion of the interior of said ejector pistons (18) constituting a core cylinder (26), with a core piston (28) in said core cylinder (26), said core pistons (28) each attached to respective core rods (32), comprising the steps ofapplying fluid pressure in said main cylinders (2) to move the main reciprocating pistons (8) forwardly and close the molds on the part line while transporting the ejector cylinders (14) and core cylinders 926) towards said part line, applying fluid pressure to said core cylinders (26) to move said core piston (28) forwardly and place the core rod or core rods (32) in the cavity between the molds, retaining fluid pressure on said ejector cylinders (14) so that the ejector rods (36, 48) attached to said core pistons (28) are flush with the mold surface, injecting a casting into the mold cavity, reversing the fluid pressure in the core cylinders (26) to retract the core pistons (28) and attached core rods (32) until the core rods (32) are retracted from the mold, reversing the fluid pressure in the main cylinders (2) to remove the molds (40, 42) attached to the main pistons (8) from the part plane, while applying fluid pressure to the ejector pistons (18) to advance the ejector pistons (18) and push the casting from respective molds on the part plane, reversing the fluid pressure in the ejector cylinder (14) to return the ejector pistons (18) and ejector rods (36, 48) to their retracted position. 